From: Shaohua Li <shli@fb.com>
Date: Fri, 9 Oct 2015 04:54:07 +0000 (-0700)
Subject: raid5: journal disk can't be removed
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=c2bb6242ece5a2a0b6bd415c1d58babe83e971a8;p=linux-beck.git

raid5: journal disk can't be removed

raid5-cache uses journal disk rdev->bdev, rdev->mddev in several places.
Don't allow journal disk disappear magically. On the other hand, we do
need to update superblock for other disks to bump up ->events, so next
time journal disk will be identified as stale.

Signed-off-by: Shaohua Li <shli@fb.com>
Signed-off-by: NeilBrown <neilb@suse.com>
---

diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 216fa3c64287..693c000e739b 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -7128,6 +7128,15 @@ static int raid5_remove_disk(struct mddev *mddev, struct md_rdev *rdev)
 	struct disk_info *p = conf->disks + number;
 
 	print_raid5_conf(conf);
+	if (test_bit(Journal, &rdev->flags)) {
+		/*
+		 * journal disk is not removable, but we need give a chance to
+		 * update superblock of other disks. Otherwise journal disk
+		 * will be considered as 'fresh'
+		 */
+		set_bit(MD_CHANGE_DEVS, &mddev->flags);
+		return -EINVAL;
+	}
 	if (rdev == p->rdev)
 		rdevp = &p->rdev;
 	else if (rdev == p->replacement)
@@ -7190,6 +7199,8 @@ static int raid5_add_disk(struct mddev *mddev, struct md_rdev *rdev)
 	int first = 0;
 	int last = conf->raid_disks - 1;
 
+	if (test_bit(Journal, &rdev->flags))
+		return -EINVAL;
 	if (mddev->recovery_disabled == conf->recovery_disabled)
 		return -EBUSY;